Sighting apparatus for ordnance.



A. BARR & W. STBOUD.

SIGHTING APPARATUS FOR ORDNANCE.

APPLICATION FILED FEB. 17. 1913'HlllllllllllIllllllll||lll1Il|l||Hll|llllllllllIllllllllllll]llllllllIllllllHllIllllllllIllllllllllll lllll|ll l l I I I I Patented Dec. 14, 1915.

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A. BARR & W. STROUD.

SIGHTING APPARATUS FOR ORDNANCE.

APPLICATION men FEB. n. 1913.

1,164,325. Patented Dec. 14, 1915.

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A. BARR & W. STROUD.

SIGHTING APPARATUS FOR ORDNANCE.

APPLlCATlON FILED FEB. l7. l9l3.

Patented Dec. 14, 1915.

4 SHEETS-SHEET 3.

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COLUMBIA PLANOGRAPH COJWASHINOTON D. h.

A. BARR & W. STROUD.

SIGHTING APPARATUS FOR ORDNANCE.

APPLICATION FILED FEB. 11. 1913.

1,164,325, Patented Dec. 14, 1915.

4 SHEETSSHEET 4- UNITED STATES PATENT OFFICE.

ARCHIBALD BARR AND WILLIAM STROUD, OF ANNIESLAND, GLASGOW, SCOTLAND.

SIGHTING APPARATUS FOR ORDNANCE.

Application filed February 17, 1913.

To all whom it may concern:

Be it known that we, ARCHIBALD BARR and VVILLIAM STROUD, subjects of theKing of Great Britain and Ireland, and both of Caxton street,Anniesland, Glasgow, Scotland, have invented new and useful Improvementsin Sighting Apparatus for Ordnance, (for which we have made applicationfor patent in Great Britain, No. 5,182, hearing date of March 1, 1912,)of which the following is a specification.

The influences that lead to the necessity of applying corrections ingun-setting may be divided into two groups, namely, internal andexternal. Internal influences being those which affect the muzzlevelocity, such as quantity of charge, temperature of charge, conditionof charge, condition of the gun, etc. External influences being thosewhich are external to the gun itself, such as rate of change of range,density and temperature of the atmosphere, velocity and direction ofwind, etc.

This invention relates to the provision of improved means for use insetting the sight of a gun and has for its object the production ofmeans comprising a scale part and an index part by the use of whichcorrections due to internal influences affecting the muzzle velocity ofthe gun can be introduced by making, for any definite change in themuzzle velocity, such, for example, as that developed under full, half,or quarter charge, one and one only definite adjustment between thescale part and the index part; and, further, to provide for theapplication of corrections required in virtue of external influencesaffecting the flight of the shot.

In applying the corrections we deal with those due to internalinfluences in one manner, and those due to external influences in adifferent manner.

The means appertaining to corrections for change ofmuzzle velocityaccording to our invention may comprise a scale of ranges of a new type,or in some cases it may comprise the equivalent of such a scale thoughthe ranges may not be marked by graduation and numbers. The means, if ina form comprising a scale, are of such a nature that the graduations (orequivalent) corresponding to constant intervals of range (1,000 yardsfor example) diminish as the range in- Specification of Letters Patent.

Patented Dec. 14, 1915.

Serial No. 748,866.

creases in an empirical manner so that if two indexes a and b at a fixeddistance apart are moved over the scale, the range read at a for anysetting of the indexes will be that for one muzzle velocity, and thatread at b will be that for another muzzle velocity with the same settingof the gunsight. Gunsight data show that such a scale can beconstructed, and they further show that intermediate muzzle velocitiescan be allowed for with very great accuracy by taking additional'indexes between a and 1). Thus, if we have a pointer movable withreference to a muzzle velocity scale, then when it is placed at a we getsettings of the gunsight corresponding to one muzzle velocity, and whenat b to another muzzle velocity, and when placed at varying pointsbetween a and b we get settings corresponding to intermediate muzzlevelocities. To construct such a scale we take two range tables for thesame gun with differing muzzle velocities, and construct a table ofelevation and the ranges corresponding to the two different muzzlevelocities, e. 9., we may have Now the problem is to construct such ascale that by shifting the index a certain constant amount we shall passfrom the one scale to the other, or in other words, to construct such ascale that if we have two indexes at a fixed distance apart, and the onereads 2270 when the second reads 830, then when the first reads 4100,the second will read 1635, and so on. It will be clear from the columnof differences that as the range increases the difference in range alsoin creases, so that the value of a specified difference in range, say,100 yards, will be much smaller at the high ranges than at the low.Moreover, it will be clear that when the range is zero, each indexshould read zeroin other words a scale of the required type to includeall ranges down to zero would be infinitely long. We therefore choose acertain minimum range, say, 1000 yards below which We do not provide atrue scale. We give here one example Range for i of Ranee for Poflitioqof l tsii e ii high M. V. gm untlon low M. V. gm anon positions onscale. on scale. on Scam 2270 199. 1 830 306.8 107. 7 4100 128. 1 1685235. s 107. 7 5610 S7. 9 2335 195. 4 107. o 6500 58. 6 2990 106. 2 107.6 7925 36. 5 3590 144.1 107. 0 8840 19. 4 4130 127. 2 107. 8 9555 5. 54645 113. 2 107. 7

The scale corresponding to these readings may then be graduated asfollows for the prmclpal divisions:

Position on scale.

To explain how such a scale may be calculat-ed it will be easier to dealwith some simple numbers representing ranges in yards. Suppose by ashift of an index mark we desire to pass from 10, 000 to 7, 000 yards or9,000 to 6,100

We may start with a purely arbitrary scale from 10000 yards until we getto 7 000 yards, the first range common to the two sets :e. g.

Position Range on scale. 10, 000 0 9, 000 10 s, 000 21 A, 000 33Position Range. on scale.

But the two partial scales so constructed do not combine well becausethe interval between the 8000 and 7000 yards graduation on the first is12 parts, whereas the interval between the 7000 and 6100 yardsgraduation on the second is 10 parts, thus the interval between the 7000and 6000 yards graduations would be roughly represented by X 10 parts or11 parts. But since the interval between the 8000 and 7 000 graduationshould be equal to that between 7000 and 6100, the in terval between the8000 and 7000 yards graduation should be less than the interval betweenthe 7000 and 6000 yards graduations, which is not the case. As a matterof fact the rate of increase in the intervals per 1000 yards between the10000, 9000, 8000 and 7000 yards graduations has been too rapid.

\Ve next try which gives an interval of 31.5 between 10000 and 7000 andthen We get 7 000 yards graduations is 11 parts for 1000 yards, whilethat between the 7000 and 0100 yards graduations is 10 parts for 900yards, or roughly 11.1 parts for 1000 yards, which is better thanbefore, but is still capable of improvement. By proceeding in this waywe succeed after a few trials in obtaining a scale suitable for thepurpose in view.

Instead of a scale ofranges constructed in the manner above described, adiagram could be constructed having a like property. Thus if we set outa scale of ranges of any type, say, a uniform scale along a verticalaxis of coordinates and a scale of ranges of the type described abovealong a horizontal axis, it will be evident that we can construct acurve such that if we move two vertical lines at a fixed distance apartalong the diagram, the points in which these lines cut the curve willrepresent, by reference to the vertical scale of ranges, the two rangesthat would be respectively reached with a given setting of the gunsightwith two given 1111M- zle velocities for the particular gun for whichthe curve has been drawn. It will be evident that such a curve can bedrawn with any type of vertical scale of ranges. Thus, for example,instead of a uniform scale of ranges we might construct the curve with areciprocal scale of ranges such as is represented by the motions of theoperating gear in a type of short base rangefinder in general use. hensuch a diagram has been constructed, it could be wrapped on the surfaceof a drum so as to constitute a spiral line thereon. If then, rotationsof the drum are made in accordance with the chosen scale of ranges (forexample, rotations by equal amounts for each 25 yards of range) apointer moved parallel to the axis of the drum so as to keep in contactwith the spiral line will move longitudinally in accordance with thecorresponding intervals on a scale of the new type described. The scalesmay then be omitted and the rotational motion of the drum and thetranslational motion of EITRlGAl. lNEiTRU MENTS L the'pointer will havethe desired relationship. Further, if a spiral groove or ridge be formedon the drum instead of the line, a piece, guided to move parallel to theaxis of the drum, can be controlled in its longitudinal motion by thegroove or ridge. In this way we shall have the desired relationshipbetween the rotation of the drum and the translational motion of theguided piece.

Some examples of constructions according to this invention will now bedescribed with reference to the accompanying drawings, in which Figure 1represents a scale determined according'to this invention. Fig. 2represents diagrammatically an application of the new type of scale to agun sight. Fig. 3 is an elevation and Fig. l a transverse section takenabout the line A B of Fig. 3, illustrating another form of gear,embodying the same principle. Figs. and 5 are together an elevation of amodified form of mechanism embodying the new features. The mechanism isshown broken in the middle so as to reduce the size of the figure. Figs.(3 and 7 represent end views of parts of the mechanism illustrated atFig. 5 after removal of the plates 121 and 122 respectively.

The scale shown in Fig. 1 is determined from the ballisticcharacteristics of the particular gun to which the sight is adapted,after the manner already described.

Fig. 2 illustrates how the new type of scale can be applied to agunsight, but for simplicity we have omitted in this figure anyarrangement of dials or mechanisms for the application of thecorrection. A disk 1, is carried on an axle 5, and operated by a handwheel 5 a shaft 8, a worm 22 and worm wheel 22 The disk 1 has a scaledetermined according to this invention marked around its edge, to beread at a pointer 4. The axle 5 also carries a disk on which a spiralgroove 9 is out, which through the medium of a pin and lever imparts therequisite inclination to the gunsight. The groove 9 would be so cut asto give the gunsight the angles corresponding to the ranges set oppositethe pointer -1l, for a given muzzle velocity. From what has been statedabove it will be evident that an alteration in the position of thepointer 4 will make the necessary alteration in the angles at which thegunsight will be set for various ranges, to suit another muzzle ve-'locity. A scale of muzzle velocities could therefore be used inconnection with the pointer so that the pointer could be set for anygiven muzzle velocity. Instead of moving the pointer 4, it will berecognized that 1 the scale disk 1 could be mounted capable of angularadjustment about the axle 5.

Figs. 3 and 4 show another arrangement having a like effect. A drum 2has formed on its surface a spiral groove or ridge 9 which, by a slider104:, controls the position of a pointer 4 working over a scale ofranges of the new type. When the drum 2 is rotated the pointer t willmove over the scale, and if the drum is so connected to the gunsightthat the angular elevations of the gunsight for any settings of thepointer are thrse required for the ranges read on the scale for onemuzzle velocity, the apparatus can be made to suit for another muzzlevelocity by a longitudinal shift of the scale (or a longitudinal shiftof the drum The corrections for influences that affect muzzle velocitycan thus be made by moving the scale longitudinally (or by moving thedrum axially).

In Fig. 5 two drums are shown, a range drum 1 and an elevation drum 2.Upon 1 is constructed a cam groove or raised cam spiral 3, into or ontowhich there is forked a piece 10.t which moves the pointer 4: forward orbackward as the drum 1 is rotated by means of its shaft 5 in ccordancewith the range communicated (say, by means of step-by-step mechanism) tothe shaft 6. The spiral cam is constructed in the manner abovedescribed. A shaft 7 communicates with or is geared to the elevatingmechanism of the gunsight. As 7 is rotated the motion is con'nnunicatedto a shaft 8 which is rigidly connected to the elevation drum 2 uponwhich is constructed a spiral line 9 of appropriate form. The form ofthis spiral will depend upon the type of mechanism used to move thegunsight relatively to the gun barrel and the arrangement of theconnection adopted between the shaft 8 and that mechanism.

In general the line may be supposed to be constructed by choosing amuzzle velocity, setting the range drum 1 successively to a number ofranges and the angle of elevation of the gunsight simultaneously to theangles corresponding to these ranges, (and marking the point to wnichthe pointer 4 comes) a line joining such points will form the spiralrequired.

The range drum 1 and the elevation drum 2- are in conformity when theline 9 has been brought by rotation of the shaft 7 until it coincideswith the pointer 4. It will be clear, however, that if the elevationdrum 2 were rotated through exactly one revolution, there would still beapparent conform ity between the two drums. This difliculty would notarise if the spiral line on the elevation drum 2 made less than one turnon the drum. A more suitable form of spiral is' obtained by making ittake more than'one turn round the drum, and in this case in order todiscriminate between the different turns a variety of methods may beadopted; the one shown in the-figure consists in providing a single turn10 upon a secondary drum 11 which is geared up to the elevation drum 2by toothed wheels, 12, 13, 14:, 15, so that 11 makes one revolution orless for the whole elevation of the gunsight. The drum 11 is axiallytranslated with the elevation drum 2 by means of a disk 16 (fixed to theelevation drum 2) which is forked between two disks 17 and 18 attachedto the secondary drum 11. In front of the secondary drum 11 is a longhorizontal slit 19 in an opaque diaphragm (not shown), so that only asmall part of the line 10 is visible at any one setting of the drum 11.To bring the elevation drum 2 into rough conformity with the range drum1, we rotate the shaft 7 until the visible part 10 of the line is abovethe pointer 1, and we can then bring the two drums into exact conformityby a further rotation of the shaft 7 until the line 9 lies exactly underthe pointer 4.

Corrections which affect muzzle velocity may be introduced by a suitabletranslation of either drum along its axis, or some of the correctionscan be introduced by translating" the one drum and some by translatingthe second drum. If several corrections are to be applied to one drum,these separate corrections may be added together by means ofdifferential gearing, or the equivalent.

To introduce any correction of the second group (which depend uponexternal influences) we may displace one or other of the drums axiallyby an amount which depends upon the magnitude of the correctionmultiplied by a function of the elevation. In the general case this maybe accomplished by means of a lever whose fulcrum is shifted by asuitably cut cam moved by the elevating gear of the gunsight.

To introduce the requisite corrections we provide means for translatingthe drums 1 and 2 axially. In Figs. 5 and 5 corrections for thefollowing are imparted to the range drum 1 :Temperature of charge,condition of charge, number of shots fired, and effect of rate of changeof range. The corrections imparted to the elevation drum 2 are thosecorresponding to the temperature and pressure of the atmosphere. It willbe clear, however, that the distribution of these corrections betweenthe two drums might have been very different, and if desirable all thecorrections might have been made by suitable translations of one of thedrums. Since the drums have to'be translated axially for thesecorrections, and since it is necessary to still maintain the gearingbetween certain portions of the mechanisms, we may make certain of thegear wheels, 0. g., 12 1-1, 19, 20, 21, 22, long in the direction oftheir axes.

The longitudinal position of the range drum 1 is determined by a pin Dand that of the elevation drum 2 by a pin D D is fixed to a lever 23 sothat the position of D depends upon the position of this lever whichagain is determined by the po sition of a pin C fixed to 23 and a slot 21 in which works the pin C attached to a nut 25. A handle 130 is for thepurpose of setting 01f the correction for, say, the condition of thecharge and a handle 26 for accomplishing the same purpose for, say, thetemperature of the charge. Upon turning the handle 130 a double pointer29 is rotated about the center of a toothed wheel 28 by a worm andworm-wheel (not shown) until the condition of the charge is correctlyindicated by the upper part of the pointer 29 upon a scale 129. Thelower point of the pointer 29 is then used as the pointer for the scaleupon 28 so that the temperature of the charge may now be set off byrotating the handle 26. In the same way a handle 27 is for setting thenumber of shots fired as marked upon a dial 30 opposite a fixed pointer31. The rotation of the handle 26 communicates its motion by means oftoothed gearing 31, 32 to a bevel 33 of differential gear 33, 34, 35. Inthe same way the handle 27 can be used to rotate the bevel 35. Thefloating bevel 34 attached to a shaft 36 thus takes up a positiondependent upon the readings of the dials 2S and 30.

The rate of change of range is set off upon a dial 37 by rotating ahandle 38, which causes a nut 39 and pin C to be moved horizontallyalong a screw 80. In this case the motion of C has not to becommunicated directly to the drum 1, because if this were done, theshift of the drum would be independent of the range, whereas the shiftof the drum ought to correspond to a change of range of (ZR T where T isthe time of flight of the shot and the low, and this may be accomplishedby shifting the fulcrum F of the bar 40 in ash which are the two slots41 and 42 embracing the two pins G and C? respectively. The fulcrum F isattached to a nut 43 which is moved upward by a screw 44 as the rangeincreases. The motion of this nut 43 in accordance with the range isaccomplished by gear 45, 19 and bevels 46, 47, in the following way :Asthe shaft 7 is rotated to bring the two drums into conformity theelevation drum 2 (to the shaft of which 45 is fixed) is rotated, andtherefore by means of 45, 19, 46, 47 and 44, the fulcrum F is raised orlowered to the correct position. It will thus be seen that the positionof the range drum 1 is only correctly set for the correction for rate ofchange of range after the two drums have been brought into conformity.

In a similar manner we may set off the corrections for the temperatureand barometric pressure of the atmosphere by moving the elevation drum 2axially. The temperature, say, is set off by a handle 50 and indicatedby a dial 51 and fixed pointer 52. The pressure is set 0H by a handle 53and indicated by a dial 54 and pointer 55. The rotation of the handle 50translates a nut 56 by means of a screw 57. Attached to the nut 56 is arack 58 gearing into a pinion 59. In the same way a rotation of thehandle 58 moves a rack 60 which also gears into 59. The parts 58, 59 and60, constitute the equivalent of a differential gear. Thus a pin C takesup a position dependent upon the values of the external temperature andpressure. In this case just as in the case of the correction for therate of change of range, the motion of the drum which it will benecessary to produce will have to be greater the greater the range. Wetherefore provide a lever 61 pivoted about 0* and having a long slot 62in which work two pins F and D The latter pin D is attached to a piece63 between two collars 64 and 65 fixed to the shaft 8, suitableprovision being made to prevent rotation of the part 63. The former pinF is carried upon a piece 66 which is suitably guided in a vertical slotof a part 67. This fulcrum F is carried up and down as the elevationdrum 2 is rotated inasmuch as the piece 66 is forked into or onto arecessed or raised spiral cam 68 formed upon a drum 69 which is rotatedby bevels 70, 71 and toothed gear 20 and 72.

We claim 1. Apparatus for use in setting a gunsight consisting of arange scale element, a gunsight elevation element, and an index element,the index element and the. range scale element being longitudinallymovable relatively to one another, one being free to so move, the othernot, such longitudinalmovement being in accordance with a scale of whichintervals of longitudinal motion corresponding to, say, 1000 yards,gradually diminish as the range increases in an empirical manner, meansfor operating the gunsight elevation element in conformity with thelongitudinal relative positions of the index and range scale elements,the index element and the range scale element being longitudinally 3d".justable relatively to one another for the purposes set forth.

2. Apparatus for setting a gunsight consisting of a range drum and anelevation drum, the range drum having a spiral guide about its surface,a piece engaging with the spiral guide mounted to move in a pathparallel to the axis of the range drum, means for rotating the rangedrum in accordance with a chosen scale of ranges, the spiral guide beingso generated that the rotations of the range drum produce a progressivemotion of the piece along its path in accordance with ranges of whichintervals, corresponding to, say, 1000 yards, gradually diminish as therange increases, in such a .way that the angular elevation of thegunsight for any range, within the capacity of the apparatus, may bemodified to the required extent by making longitudinal adjustments ofthe drums for introducing the corrections required, the elevation drumhaving a spiral line upon its surface and the piece a pointer to bebrought into conformity therewith, means for discriminating the correctturn of the spiral line on the elevation drum, mechanism fortransmitting motion from the elevation drum to the sight, and means foreffecting longitudinal adjustments of the drums for introducing thecorrections required in virtue of internal and external influences.

ARCHIBALD BARR.

WILLIAM STROUD.

Witnesses:

A. DAVIES, C. WVILsoN.

Copies of this patent may he obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

